RFR: 8179268: Factor out AdaptiveSizePolicy from top-level interfaces CollectorPolicy and CollectedHeap

[Roman Kennke]

AdaptiveSizePolicy is not used/called from outside the GCs, and not all
GCs need them. It makes sense to remove it from the CollectedHeap and
CollectorPolicy interfaces and move them down to the actual subclasses
that used them.

I moved AdaptiveSizePolicyOutput to parallelScavengeHeap.hpp, it's only
used/implemented in the parallel GC. Also, I made this class AllStatic
(was StackObj)

Tested by running hotspot_gc jtreg tests without regressions.

http://cr.openjdk.java.net/~rkennke/8179268/webrev.00/
<http://cr.openjdk.java.net/%7Erkennke/8179268/webrev.00/>

Roman